The challenge was to build a game whose source would fit inside a tweet:

I challenge you to make a game whose source fits in a single tweet

And here’s one of the responses:

main(b){char s[9];b=0;for(;b<12&&(int)(s+5)!=(int)s;){b%4||gets(s+5);b<4&&(s[b]=’a’+rand()%4);putchar(“-x”[s[b++%4+5]==s[b%4]]);}}

Build it, run it, you’ll end up with this game here. Crazy.